One last rain shower on the way for SLO County?

In yet another example of the rain year that won’t quit, forecasters say there is a small chance that showers will fall across San Luis Obispo County on Wednesday.

An unseasonably cool storm system is making its way down the West Coast from the Gulf of Alaska, local forecaster John Lindsey said.

It is expected to arrive on the Central Coast sometime this afternoon or evening, bringing with it a deep marine layer of fog and cooler temperatures.

Drizzle or even showers are possible Wednesday morning, and the daytime high in San Luis Obispo is expected to be 68 degrees — about 10 degrees below normal.

“The farther north in San Luis Obispo County you are, the greater chance of receiving some measurable precipitation,” Lindsey said.

The 2010-11 rain year officially ends Thursday. SLOweather.com, a private firm that keeps rain totals for The Tribune, has measured 38.03 inches of rain this year, well above the 24.36 average.

This June has already received record-breaking rain. Over the weekend of June 4 and 5, 1.05 inches were recorded at Cal Poly. That set a new mark for total rainfall for the month. The previous record of 0.80 was set in 1991.

The clouds will start to move out late Wednesday, and temperatures will warm up in time for the Fourth of July weekend, Lindsey said.

The National Weather Forecast said an “enormous” high pressure area will set up over the southern half of the nation. High pressure yields clear, dry and warm weather.

The high temperature in Paso Robles by Sunday is expected to top 100 degrees, while San Luis Obispo is expected to heat back up to near 80.